Special purpose electric motor



25, 5 G. w. HENNIGH ETAL 2,650,314

SPECIAL PURPOSE ELECTRIC MOTOR Filed Feb. 12, 1952 J2 i 5e Patented Aug.25, 1953 UNITED STATES PATENT OFFICE George W. Hennigh and Harry D.Ridge, Long Beach, Calif.

Application February 12, 1952, Serial No. 271,180

1 Claim.

The present invention relates to a special purpose electric motorespecially adapted for use under extremely adverse operating conditions.

One example of such adverse operating conditions occurs in the art ofoil or gas well drilling or servicing. In the drilling or servicing ofoil and gas wells, it is frequently necessary to lower into the wellbore certain instruments or tools, as for example, surveyinginstruments. Such an operation is normally not especially difiicultwhere the well bore is substantially vertical. When, however, the wellbore is of the Whipstocked or directional type, it may include extremevertical discontinuities; some portions of such wells actuallyapproaching or exceeding the horizontal. Accordingly, it commonly occursthat considerable difficulty is encountered when lowering tools into awhipstocked well bore.

The usual manner of lowering a tool into a well bore is by means of acable. Where, however, the bore is of the whipstocked type, havingportions which veer far from the vertical, it becomes necessary to forcethe tool down the well bore by means of a string of tubing. Since suchstring must necessarily be made up of a great number of individuallengths of tubing, considerable time and effort is required for thisoperation. Accordingly, it is far more desirable to be able to lower thetool by means of a cable.

It has been suggested therefore, that in order to make it possible toutilize a cable for lowering a well tool into a whipstocked well bore,the tool be coupled to a source of traction adapted to pull the toolthrough the well bore. The source of traction may take the form of anelectric motor, which motor receives its power from the same cableutilized to support the tool. This motor is adapted to rotate apropeller whereby the motor and tool may be pulled downwardly throughthe fluid in the well bore. When the tool is to be removed, thedirection of rotation of the motor and propeller may be reversed.

The use of a conventional electric motor for the above-described purposeis not practical in view of the problems involved in providing aneffective seal for the motor windings, and also because of the difhcultyinvolved in cooling the motor and its bearings. In this regard, theconentional electric motor must be sealed from the well fluids, andaccordingly a seal must be provided for its shaft. Such sealing of itsshaft is extremely difficult, however, inasmuch as the pressuredifferential may exceed 1700 pounds per square inch, while thetemperature may exceed 120 Fahrenheit. These pressure and tempera- 2ture conditions result in rapid wearing of the shaft seal as well asconsiderable power loss as the shaft is rotated. Such conditions of heatlikewise results in a short service life for the motor windings andbearings.

It is a major object of the present invention to provide an electricmotor which may be used under conditions of extreme pressure andtemperature without the use of a shaft seal.

Another object of the present invention is to provide an electric motorwhich may be utilized under conditions of extreme pressure andtemperature, and yet which will have a long service life.

It is a more particular object of the present invention to provide anelectric motor which may be effectively utilized in a well borecontaining fluid existing at a high pressure and temperature.

These and other objects and advantages of the pr sent invention willbecome apparent from the following description of a preferred embodimentthereof, taken in conjunction with the appended drawings, wherein:

Figure 1 is a longitudinal side View, partly broken away in section,showing the novel special purpose electric motor of the presentinvention as embodied in a special well bore apparatus; and,

Figure 2 is a view showing the manner of operation of the well boreapparatus of Figure 1.

Referring to the drawings, the novel special purpose motor of thepresent invention is shown incorporated in a well bore apparatusdesignated A. This motor broadly comprises a generally cylindricalprimary I0 and a generally tubular secondary I2 coaxial with andconcentric to the primary. The secondary i2 is adapted for rotationrelative to the primary l0 about their common axis. Front and rear ballbearings, l8 and 2 .3, respectively, are shown interposed between theprimary l0 and the secondary 12 whereby such rotation may take place.The primary i0 is connectible to a source of electric power (not shown)by conduit means 16.

More particularly, the primary I0 includes windings 22 disposed in agenerally cylindrical configuration about a longitudinal axis, whichwindings are supported upon a fixed shaft 24 coinciding with thelongitudinal axis. The secondary l2 includes a plurality oflongitudinally extending conductor bars 26 disposed in a generallytubular configuration coaxial with and concentric to the windings 22.Preferably, the rear portion of the shaft 24 is hollow whereby to housethe conduit means IS. A non-magnetic and fluid-tight shield 28 is shownenclosing the windings 22 of the primary In for a purpose to be setforth hereinafter. From this description it will be apparent that uponconnection of the conduit means IS with a source of electric power therewill take place relative rotation between the primary Ill and thesecondary l2.

As mentioned previously hereinbefore, the special purpose motor of thepresent invention is especially adapted for use with a well boreapparatus A. Referring to Figure 2, this apparatus is shown disposed ina whip-stocked well bore 32. The slope of this well bore is seen to beof such a nature as to prevent the efiicient use of a cable as loweringmeans for the apparatus A. It should be understood that this slope isexaggerated in Figure 2 in the interest of clarity.

The apparatus A is supported by a cable 34, which cable in turn isconnected to a surfacelocated manipulating device 36. This cable ispreferably of the type having integral electric conducting wires. InFigure 2 the apparatus A is shown in the process of being loweredthrough the well bore 32, which well bore is seen to contain fluid 38.As mentioned previously hereinbefore, such fluid commonly exists at ahigh pressure and temperature.

Referring again to Figure 1, the apparatus A may comprise a stationarymember 40 wherein is located any desired instruments or tools, such asfor example, a well surveying instrument. If such instrument is of theelectrically perated type, it may readily receive current from the cable34. Stationary member 40 is shown as mounting outwardly-bowed springs 42for centralizing the apparatus A relative to the well bore 32, as wellas for restraining rotation of the stationary member relative to suchbore. A bracket 44 secured to the rear of the stationary member 40supports a mounting loop 46 for the cable 34. The stationary member 40mounts at its forward portion, a rotatable member 46 having blades 48,which blades are seen to be curved whereby rotation of the rotatablemember will cause the apparatus to be pulled through the well bore fluid33. Preferably, these blades 48 will be removable relative to therotatable member 43 whereby their replacement is facilitated.

The primary [0 is shown rigidly connected to the stationary member 45 bymeans of the shaft 24, which shaft is in turn rigidly afiixed to a boss4i formed on the stationary member, as by a stud bolt 43. Preferably,the shaft 24 will extend beyond the front end of the primary windings 22whereby it may rotatably support the front portion of the rotatablemember 45. To this end the inner race of the bearing I8 is seen to berigidly affixed to the front of the shaft, while its outer race is shownpositioned within a spider 49, which spider is formed upon the rotatablemember. Similarly, the inner race of the bearing 26 is shown rigidlyafiixed to the rear portion of the shaft, while its outer race ispositioned within a spider i. Preferably, this spider 5i will beremovably secured within the stationary member, as by bolts 52. The twospiders 49 and 5| define between them an annular motor compartment 53wherein is rigidly mounted the secondary l2.

Preferably, the nose of the stationary member will be formed withapertures 54, the spider 49 with bores 55, and the side walls withapertures .4 56. With this arrangement, upon rotation of the primary l0,fluid may pass through the annular gap 54' separating the primary andthe secondary, as indicated by the arrows in Figure l. The fluid passingthrough this annular gap will have a heat-transferring relationship withboth the primary and the secondary whereby to reduce the temperaturethereof.

In operation, the apparatus A will be lowered into the well bore 32 bymeans of the manipulating device 36. When the fluid-containing portionof the well bore is reached, electric current will be transmitted to theprimary windings 22 through the cable 34. At this point the secondaryl2, and hence the rotatable member 46, will commence rotation relativeto the stationary member 40. Such rotation will cause the blades 48 topull the apparatus A downwardly through the well bore. During this time,the primary windings 22 and the bearings l8 and 20 will be cooled by thewell bore fluid passing through the annular gap 54. This fluid will beprevented from contact with the primary windings 22 by the non-magneticfluid-tight shield 28, which shield may preferably be formed of copper.When it is desired to retrieve the apparatus A, either the direction ofrotation of the secondary [2 may be reversed whereby the blade 48 willtend to push the tool out of the well bore, or alternately, the cable 34alone may be used to pull the apparatus upwardly out of the well bore.

It will be apparent to those skilled in the art that the novel electricmotor of the present invention may be utilized for many other specialpurposes apart from the apparatus A described hereinabove. For example,this motor may prove very well adapted for use with pumps and blowers,especially where such devices must operate under extremely adversepressure and temperature conditions. Accordingly, we do not wish to belimited to the specific structural details described hereinbefore, butsolely by the scope of the following claim.

We claim:

Apparatus for pulling a tool into a well bore comprising: a cylindricalbase member which is adapted to be lowered into a fluid-containing wellbore and to house said tool; a plurality of outwardly-bowed flexible,longitudinally extending spring elements for engaging the walls of saidwell bore to restrain rotation of said base member relative to thelongitudinal axis of the well bore; an electric current-carrying cablesecured to the rear of said base member for lowering said apparatus intosaid well bore; a rotatable cylindrical member disposed forwardly ofsaid base member, said rotatable member having a motor compartment; acoaxial hollow shaft rigidly mounted at its rear end to the front ofsaid base member and extending forwardly therefrom; blade meansremovably attached to the front portion of said rotatable member, saidblade means being adapted to pull said apparatus through said well boreupon rotation of said rotatable member; bearing means interposed betweensaid shaft and said rotatable member at the front and at the rear ofsaid windings whereby said rotatable member may rotate upon said shaft;a coaxial primary formed of windings disposed in a generally cylindricalconfiguration about said shaft within said motor compartment; conduitmeans extending rearwardly through said shaft from said primary forconnection to said cable in order that electric current may be suppliedto said primary; a non-magnetic fluid-tight shield enclosing saidprimary windings; a secondary including a plurality of longitudinallyextending conductor bars arranged in a generally tubular configurationcoaxial with and concentric to said primary windings, said secondarybeing rigidly mounted within said motor compartment; intake aperturesformed in the front portion of said rotatable member in communicationwith the front of the annular gap separating said primary and saidsecondary; and, outlet apertures formed in the rear portion of saidrotatable member in communication with the rear of said annular gapwhereby said fluid may pass through said annular gap inheat-transferring relationship during rotation of said rotatable member.

GEORGE W. HENNIGH. HARRY D. RIDGE.

References Cited in the file of this patent UNITED STATES PATENTS NumberNumber Name Date Jigouzo July 12, 1904 McKee Sept. 1, 1931 Gold et a1June 20, 1933 Meyers Oct. 7, 1941 Millard Sept. 3, 1946 Hervert Jan. 31,1950 FOREIGN PATENTS Country Date Germany Nov. 12, 1942

